package org.apache.lucene.document;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.Searcher;

/**
 * Documents are the unit of indexing and search.
 * 
 * A Document is a set of fields. Each field has a name and a textual value. A
 * field may be {@link Fieldable#isStored() stored} with the document, in which
 * case it is returned with search hits on the document. Thus each document
 * should typically contain one or more stored fields which uniquely identify
 * it.
 * 
 * <p>
 * Note that fields which are <i>not</i> {@link Fieldable#isStored() stored} are
 * <i>not</i> available in documents retrieved from the index, e.g. with
 * {@link ScoreDoc#doc}, {@link Searcher#doc(int)} or
 * {@link IndexReader#document(int)}.
 */

public final class Document implements java.io.Serializable {
	private static final long serialVersionUID = -1606577241438434706L;
	List<Fieldable> fields = new ArrayList<Fieldable>();
	private float boost = 1.0f;

	/** Constructs a new document with no fields. */
	public Document() {
	}

	/**
	 * Sets a boost factor for hits on any field of this document. This value
	 * will be multiplied into the score of all hits on this document.
	 * 
	 * <p>
	 * The default value is 1.0.
	 * 
	 * <p>
	 * Values are multiplied into the value of {@link Fieldable#getBoost()} of
	 * each field in this document. Thus, this method in effect sets a default
	 * boost for the fields of this document.
	 * 
	 * @see Fieldable#setBoost(float)
	 */
	public void setBoost(float boost) {
		this.boost = boost;
	}

	/**
	 * Returns, at indexing time, the boost factor as set by
	 * {@link #setBoost(float)}.
	 * 
	 * <p>
	 * Note that once a document is indexed this value is no longer available
	 * from the index. At search time, for retrieved documents, this method
	 * always returns 1. This however does not mean that the boost value set at
	 * indexing time was ignored - it was just combined with other indexing time
	 * factors and stored elsewhere, for better indexing and search performance.
	 * (For more information see the "norm(t,d)" part of the scoring formula in
	 * {@link org.apache.lucene.search.Similarity Similarity}.)
	 * 
	 * @see #setBoost(float)
	 */
	public float getBoost() {
		return boost;
	}

	/**
	 * <p>
	 * Adds a field to a document. Several fields may be added with the same
	 * name. In this case, if the fields are indexed, their text is treated as
	 * though appended for the purposes of search.
	 * </p>
	 * <p>
	 * Note that add like the removeField(s) methods only makes sense prior to
	 * adding a document to an index. These methods cannot be used to change the
	 * content of an existing index! In order to achieve this, a document has to
	 * be deleted from an index and a new changed version of that document has
	 * to be added.
	 * </p>
	 */
	public final void add(Fieldable field) {
		fields.add(field);
	}

	/**
	 * <p>
	 * Removes field with the specified name from the document. If multiple
	 * fields exist with this name, this method removes the first field that has
	 * been added. If there is no field with the specified name, the document
	 * remains unchanged.
	 * </p>
	 * <p>
	 * Note that the removeField(s) methods like the add method only make sense
	 * prior to adding a document to an index. These methods cannot be used to
	 * change the content of an existing index! In order to achieve this, a
	 * document has to be deleted from an index and a new changed version of
	 * that document has to be added.
	 * </p>
	 */
	public final void removeField(String name) {
		Iterator<Fieldable> it = fields.iterator();
		while (it.hasNext()) {
			Fieldable field = it.next();
			if (field.name().equals(name)) {
				it.remove();
				return;
			}
		}
	}

	/**
	 * <p>
	 * Removes all fields with the given name from the document. If there is no
	 * field with the specified name, the document remains unchanged.
	 * </p>
	 * <p>
	 * Note that the removeField(s) methods like the add method only make sense
	 * prior to adding a document to an index. These methods cannot be used to
	 * change the content of an existing index! In order to achieve this, a
	 * document has to be deleted from an index and a new changed version of
	 * that document has to be added.
	 * </p>
	 */
	public final void removeFields(String name) {
		Iterator<Fieldable> it = fields.iterator();
		while (it.hasNext()) {
			Fieldable field = it.next();
			if (field.name().equals(name)) {
				it.remove();
			}
		}
	}

	/**
	 * Returns a field with the given name if any exist in this document, or
	 * null. If multiple fields exists with this name, this method returns the
	 * first value added. Do not use this method with lazy loaded fields.
	 */
	public final Field getField(String name) {
		return (Field) getFieldable(name);
	}

	/**
	 * Returns a field with the given name if any exist in this document, or
	 * null. If multiple fields exists with this name, this method returns the
	 * first value added.
	 */
	public Fieldable getFieldable(String name) {
		for (Fieldable field : fields) {
			if (field.name().equals(name))
				return field;
		}
		return null;
	}

	/**
	 * Returns the string value of the field with the given name if any exist in
	 * this document, or null. If multiple fields exist with this name, this
	 * method returns the first value added. If only binary fields with this
	 * name exist, returns null.
	 */
	public final String get(String name) {
		for (Fieldable field : fields) {
			if (field.name().equals(name) && (!field.isBinary()))
				return field.stringValue();
		}
		return null;
	}

	/**
	 * Returns a List of all the fields in a document.
	 * <p>
	 * Note that fields which are <i>not</i> {@link Fieldable#isStored() stored}
	 * are <i>not</i> available in documents retrieved from the index, e.g.
	 * {@link Searcher#doc(int)} or {@link IndexReader#document(int)}.
	 */
	public final List<Fieldable> getFields() {
		return fields;
	}

	private final static Field[] NO_FIELDS = new Field[0];

	/**
	 * Returns an array of {@link Field}s with the given name. Do not use with
	 * lazy loaded fields. This method returns an empty array when there are no
	 * matching fields. It never returns null.
	 * 
	 * @param name
	 *            the name of the field
	 * @return a <code>Field[]</code> array
	 */
	public final Field[] getFields(String name) {
		List<Field> result = new ArrayList<Field>();
		for (Fieldable field : fields) {
			if (field.name().equals(name)) {
				result.add((Field) field);
			}
		}

		if (result.size() == 0)
			return NO_FIELDS;

		return result.toArray(new Field[result.size()]);
	}

	private final static Fieldable[] NO_FIELDABLES = new Fieldable[0];

	/**
	 * Returns an array of {@link Fieldable}s with the given name. This method
	 * returns an empty array when there are no matching fields. It never
	 * returns null.
	 * 
	 * @param name
	 *            the name of the field
	 * @return a <code>Fieldable[]</code> array
	 */
	public Fieldable[] getFieldables(String name) {
		List<Fieldable> result = new ArrayList<Fieldable>();
		for (Fieldable field : fields) {
			if (field.name().equals(name)) {
				result.add(field);
			}
		}

		if (result.size() == 0)
			return NO_FIELDABLES;

		return result.toArray(new Fieldable[result.size()]);
	}

	private final static String[] NO_STRINGS = new String[0];

	/**
	 * Returns an array of values of the field specified as the method
	 * parameter. This method returns an empty array when there are no matching
	 * fields. It never returns null.
	 * 
	 * @param name
	 *            the name of the field
	 * @return a <code>String[]</code> of field values
	 */
	public final String[] getValues(String name) {
		List<String> result = new ArrayList<String>();
		for (Fieldable field : fields) {
			if (field.name().equals(name) && (!field.isBinary()))
				result.add(field.stringValue());
		}

		if (result.size() == 0)
			return NO_STRINGS;

		return result.toArray(new String[result.size()]);
	}

	private final static byte[][] NO_BYTES = new byte[0][];

	/**
	 * Returns an array of byte arrays for of the fields that have the name
	 * specified as the method parameter. This method returns an empty array
	 * when there are no matching fields. It never returns null.
	 * 
	 * @param name
	 *            the name of the field
	 * @return a <code>byte[][]</code> of binary field values
	 */
	public final byte[][] getBinaryValues(String name) {
		List<byte[]> result = new ArrayList<byte[]>();
		for (Fieldable field : fields) {
			if (field.name().equals(name) && (field.isBinary()))
				result.add(field.getBinaryValue());
		}

		if (result.size() == 0)
			return NO_BYTES;

		return result.toArray(new byte[result.size()][]);
	}

	/**
	 * Returns an array of bytes for the first (or only) field that has the name
	 * specified as the method parameter. This method will return
	 * <code>null</code> if no binary fields with the specified name are
	 * available. There may be non-binary fields with the same name.
	 * 
	 * @param name
	 *            the name of the field.
	 * @return a <code>byte[]</code> containing the binary field value or
	 *         <code>null</code>
	 */
	public final byte[] getBinaryValue(String name) {
		for (Fieldable field : fields) {
			if (field.name().equals(name) && (field.isBinary()))
				return field.getBinaryValue();
		}
		return null;
	}

	/** Prints the fields of a document for human consumption. */
	@Override
	public final String toString() {
		StringBuilder buffer = new StringBuilder();
		buffer.append("Document<");
		for (int i = 0; i < fields.size(); i++) {
			Fieldable field = fields.get(i);
			buffer.append(field.toString());
			if (i != fields.size() - 1)
				buffer.append(" ");
		}
		buffer.append(">");
		return buffer.toString();
	}
}
